It is conventional practice to mount instruments, optical devices, or manufactured parts on a rotatable table, and to provide means adjustably to rotate them for inspection or alignment. The objective of these mounts is to enable the device to be rotated around an axis and placed in a selected rotary position.
Such mounts nearly universally involve backlash, which is slack in the system, such that there is a delay in reversal of the mount when the adjustment means is reversed. This is at least an annoyance. It is desirable that the adjustment means and the mount be very closely coupled so the operator can quickly and reliably return to a position which he may inadvertently have passed without having to take up system slack.
Also, it is desirable for the mount to be able to be grossly rotated quickly, and then to be finely adjusted.
This apparatus is also useful as a power transmission
It is an object of this invention to provide the above features and advantages.